Automatic milling cutter grinder



` D. A. CARGILL 2,610,449

AUTOMATIC MILLING CUTTER GRINDER Sept. 16, 1952 3 SheetTs-Sheet 1 ,FiledNov. e, i948 Si l M i w i t 'u' I u 2 V l llwentor a/nQZf// D. A.CARGILL -AUTOMATIC MILLING CUTTER GRINDER Sgpt. 16, 1952 3 sheets-sheet2 Filed Nov. 6, 1948 nuentor 19m www (Ittornegs Sept. 16, 1952 D. A.CARGILI. 2,610,449

AHIDOMATIC MILLING CUTTER GR 1NDER Filed Nov. 6, 1948 5 Sheets-Sheet 5Patented Sept. 16, 1952 UNITED STATES PATENT OFFICE Don A. Cargill,Birmingham, Mich., assigner vLto General Motors Corporation, Detroit,AMich, -a

corporation of Delaware Application November 6, 1948, Serialhlm-58,719

. A11 Claims.

This .invention relates ito grinding .machines and 'particularly :to .amachine 'for successively grinding a `r.plurality .of .circumferentially`:spaced 'and similarly inclined surfaces on a work piece, 'such as "forexample, the tooth faces on a vface millingcutter.

'It'isthegeneral object of 'the invention to pro vide -such a machinewith ywhich such operations can be performed more accurately and rapidlythan A*has been possible or ypracticable heretofore.

.More specifically 'it is an object of the .invention to :provide :amachine of cheap and simple construction which Aperforms -suchvoperations with asurface grinding action and in which the workautomatically indexed `and vfed to the Agrndingwlheel.

'The means rby'which these .and other objects and advantages are'obtained Lis vclearly described hereinafter, reference being made tothe drawings,in':which: f

"Figure 1=1 is an elevational yview of a Amachine forming a specificembodiment of my invention, Withfparts vbroken away-and 'insection andshowing theoutlinelo'f la ymilling cutter installed thereonlforgrinding.

Figure 2 is an enlarged-view of a portion of the machine taken from line2-2 of Figure l, with parts broken yawayand in section.

Figure 73 iis an enlarged fragmentary view in perspective showingcertain details of the machines work Tfeeding mechanism.

Figure 4 is van enlarged view 'of a portion of themac'hine taken fromline 14--4 of Figure l, with parts 'ibroken -away and 'in section.

'Figure A5 viis an elevational view illustrating a tooth or" va millingcutter Y:being ground on `the machine in various stages of its movementinto andfoutrof engagement with the grinding Wheel.

'Figurei showsanenlargement of the working surface contour-oiga .rotarycam employed in the machine, `'and a lift velocity diagram thereof.

Referring to 'the drawings, ythe machine comprisesastationarysupporting'structure or frame 2 in'which is Imounted a rotatably andreciprocably-drivenvertical spindle 4 adapted to lcarry a milling cutter6 or :other work piece into intermittent engagement withv an vabradingmember such :as a vgrindingwheel 8. The latter may, as shown, .bedirectly 'drivenbythe spindle .or .shaft lllof an -electric motor I3supported through :its spindle bearing I-2 and .adjustably positionedand secured to the v-frame 2 by a clamp I4.

The Vframe y-2 forms -a box-like enclosure 'for the movable parts`employed in controlling the movements of the spindle 4, vand maybesimply and vinexpensively formed of top andbottomhorizontal plates I6`and i8, welded or otherwisepermanently vsecured .to a vertical -plate20 which forms the back of 4the enclosure `and extends above the same toprovide a rigid mounting -for tliegrinding wheel motor I3.Removable-plates 22, .Z4-and 26 are provided "tolcomplete *the fremaining three sides'of the enclosure.

The top plate I6 of the frame 2 has an aperture through which extends acylindrical nsleeve member 28 which-is `anchoredat-its -upper end'to'thetop plate rI6 and anchored at its lower end "to a horizontal bracemember 30 which -is anchored to the vertical plate 20 and is also tiedtothe top plate I6 by a vertical brace member 432. Lining the sleevemember 2-8 is an `upper bushing 34 which journals the spindle 4.

The upper end of the spindle l4 isp-rovided with a .reduced diameterportion 35 having means such as the Vstud 36 and nut 38 for coaxiallnysecuring a work piece such asa milling cutter 6 having cutting teeth` 1.f

ASpaced vbelow l the sleeve member 28 and Vin alignment with the upperbushing34 therein is 'a lower bushing `4l] flxedly supported vin a lringmember 42^which is anchored lby a second horizontal brace member `44tothe vertical plate 20 and verticalbrace member32. The upper end ofthelower ibushing 40 Vis angedoutwardlyand provides a thrust bearingsurface'for a rotatively movable ring 46 4disposed coaxially of the-spindle 4 vand :having a worm wheel 48 removably secured thereto as byscrews 49 and 5l. The spindle 4 is vfreely'slidable longitudinallythrough the movable ring 46 butis'locked against relative `rotationtherewith by ,the 'key 50 which is secured by Athe screw 5 ,2 in arecess -54 .in thebore of the .ring 4.6 .andprojects into .a long(groove .56 .on the ex terior ofthe spindle'4.

Inimesh `withthe .Worm wheel 48isa Worm ylit on a shaftp journaled .inthe vertical plate 2li and 'in a bearngsupport plate S82 which isanchored to the Ibottom plate lil .and to the two horizontal bracemembers .3.0 and 44. Theshaft 6|),as shown, extends 'through thevertical plate 20 -and 'is Vdrivably .connectedto-a motorl, .as by thebelt -running over pulleys 68 and 18. l

The spindle .4 Ais vertically supported by a -lever 'l2 Vdisposed.transverselyof the spindle axis vbelow thelowerendof the spindle.ThebottQm end-of thespindle 4 is Aprovided centrally .thereof withfaconical recess .orsoclet 14 lftoreceive a ball f7.6 whichrests onevariable thicknessspacermember such-as `the .Wedge -18 ,-whioh 1in turnrests Vonthe lever 1.2. The lwedge 18 extends transverselyof the lever12 and is laterally supported thereon by two guide blocks 80 and 82,most clearly shown in Figure 3, which are xedly secured to the frame 2through a vertical brace member 84 extending from the ring member 42 tothe bottom plate I3. The Wedge 18 is slidable transversely of the lever12 and also vertically in a groove 86 formed by an upwardly open recessin the side of the guide block 82 adjacent the guide block 80. Thegroove 86 is of sufficient depth both to provide ample lateral supportfor the wedge 10 when the lever 12 is in its uppermost operativeposition, and to prevent the wedge from bottoming therein when the leveris in its lowermost position. The top faces of the guide blocks 80 and82 may be relieved or notched as shown at 88 in Figure 3, to preventtheir interfering with the ball 16 when the lever is in its lowermostposition. As best shown in Figures 2 and 3, the bottom face 90 of thewedge 18 is rounded t0 provide approximately line contact with the lever12, and the top face 92 on which the ball 16 rests is inclined in adirection longitudinally of the wedge to provide for variably adjustingthe height of the spindle relative to the lever 12. Moving the wedge 18to the-right as viewed in Figure 2 operates to raise the reciprocatorystroke of the spindle and thereby feed the milling cutter 6 (or otherwork) to the grinding wheel 8.

The lever 12 is fulcrumed at one end on a pin 54 for oscillatorymovement in a plane through the longitudinal axis of the spindle 4 inresponse to movements of a single lobed rotary cam 06 upon which itsopposite end rests and which is drivably carried on acarnshaft 08journaled in the plates 20 and 62. Camshaft 03 and shaft 60 arepositively geared together, as by intermeshing gears and |02 removablyxed thereto respectively, at a drive ratio such that camshaft 98 makesthe same number of revolutions per each revolution of the spindle 4 asthe number of teeth on the milling cutter 6 being ground. When millingcutters having greater or lesser numbers of teeth are to be ground, thegearing together of camshaft 98 and shaft 60 must be changedaccordingly, in order that the same relationship is maintained betweenthe number of cutter teeth and the speed of the camshaft. In the case ofthe particular machine shown, such a change in gearing is accomplishedby removing. gears |00 'and |02 from their respective shafts andsubstituting other gears (not shown) providing the required drivingratio.

The cam 96 is designed to operate in the direction of the arrow |04. Asshown in Figure 6, a contour for the working surface |06 which hasproved entirely satisfactory consists of successively adjacent sectionsblended together and providing respectively 40 of uniform accelerationlift (320-360), 100 of uniform velocitylift (360- 100), 40 of uniformdeceleration lift (loot-140) 60 of uniform acceleration drop (140-200)60 of uniform velocity drop (200-260), and 60 of uniform decelerationdrop. While various other contours might be employed for the workingysurface |06, that which is illustrated and just described has twoadvantageous features which are preferably to be retained in anymodification thereof, namely, a, single lobe, and a uniform velocitylift section. A single lobe cam insures equal lift of the spindle 4(through the lever 12) for each tooth of the milling cutter beingground, thereby eliminating the camfrom any possible contribution tomilling cutter run-out (variation in height between respective teeth)during grinding. And the uniform velocity lift section of the 4. workingface |06 synchronizes the rate of lift of the spindle 4 with the rate ofrotation of the spindle, and causes the various teeth 1 of the millingcutter 6 being ground -to move in respective parallel planes during thatportion of each revolution of the cam 96. Figure 5 illustrates theprogressive movement of a milling cutter tooth 1 as it is broughtinto'and out of engagement with the working face |05 of the grindingwheel 8, the line |01 representing the plane within which that portionof the movement occurs While the constant velocity lift section of thecam working face |06ris in operation.

The maximiun lift height of the cam working face |06, which with thecontour illustrated in Figure 6 occurs at the 140 position, may bechosen in accordance with the size of the milling cutters intended to beground on the machine. For grinding the standard range of face millingcutters used in machining automotive crankcases, cylinder heads, and thelike, a maximum lift height of approximately 1A; of an inch was found tobe satisfactory in the machine shown.

The pin 04 which serves as the fulcrum for the lever 12 is mounted in abracket |08 which is releasably clamped, as by a plate 0 and bolts ||2and H4, to a horizontal rail llxedly secured to the frame 2 through thevertical brace member 84 and a pedestal IIS. The location of the bracket|08 along the rail |10 determines the distance of the fulcrum pin 94from the spindle 4 and cam 06, and thus the veffective length of thelever 12, which in turn determines the length of stroke of the spindle 4effected by the camV 06. And, since the cam 06 is geared to the rotationof the spindle 4, the length of the stroke of the spindle determines thespeed of its reciprocatory movement. Further, since the rate of lift ofthe spindle is synchronized with its speed of rotation during theportion of the stroke when the uniform velocity lift section of the cam06 is in service, by increasing or decreasing the reciprocatory strokean adjustment is obtained of the inclination, relative to the spindleaxis, of the parallel planes through which the milling cutter teeth moveduring that portion ofv the stroke.

An externally threaded lead screw |20, having a C-shaped extension |22slidably supported in a groove |24 between the guide blocks 80 and 82,is provided for movably adjusting the location of the wedge 18transversely of the lever 12. The extension |22 embraces opposite endsand one side of the wedge 18, as shown in Figure 3, the wedge being freeto move vertically relative thereto in response to the oscillatorymovements of the lever 12. Threadedly engaging the lead screw |20 is acircular nut |26 which is free to rotate thereon but is anchoredlongitudinally thereof by a finger member |28 engaging a peripheralgroove |30 therein and fxedly secured as by the screw |32 to thestationary guide block 82. The nut |20 has outwardly extending flangeportions |34 and |36 defining the groove |30 and an externally threadedreduced diameter portion |38 extending coaxially thereof through anaperture |40 in the removable front plate 24 of the frame 2. A crank |42is connected to the reduced diameter Iportion |38 for manually turningthe nut |20. Threadedly engaging the reduced diameter por-y tion |38 ofthe nut |26 is an internally threaded lock nut |44 journaled in theaperture |40 and having an outwardly extending flange portion |46disposed opposite the flange portion |34 of the nut |26. Between theflange portions 46 and tionally 4clutched between acid-44.9

A|34 -and journaled Aon ashoulder |43 on the .-nut |20 isa peripherallytoothed member or star wheel |50 'which "is adapted to Aloe .rotated -instep-by-step Vfashion vwith each successive yrotation'ofthe spindle-4 byan arm |5| fixed to the movable ring 46 as by the screw 5|. A hand wheel|52, Vjournaled `on the lock nut |44 and slidable longitudinallythereof, is lprovided Ywith a-.set screw |54 which -canfbe releasablybrought into engagement .with a slot y|50 inthe lock nut Y whenever itis desired toy rotate vthe `latter `in order toelfect 4aclutchingengagement or disengagement ofthe starwheel r|5|) with respectto the .nut |26. When the star wh-eel `|50 Ais fricl the respective angeportions .|34 Yand |48 of the nuts '|26 and |44, v-the nut rotatesapredetermined incr-,ement at the beginning .(or end) of each revolutionof the spindle 4, lwhich in turn, effects an incremental axial-movementof the lead screw and y-a yresultant incremental Iraising ofthe reciprocatory stroke of the spindle. s

The operation of `the machine, although .believed to be already`apparent from the description heretoforegiven of the .functions of itsvarious elements, will now ing cutter 6 or other work-piecehavingprojections in the nature of cutter teeth V1 to be ground is firstplaced on the vupper end of `the yspindle 4 and clamped securely-by thenut 3.0. By adjustment of the-clamp i4 relative to the frame back membervr20 the .grinding wheel .8 is positioned over .the work, such. that thewheel working face |05 is inclined from the horizontal by the amount ofthe clearance angle with which it is desired to provide the cutter teeth.1, and such that 'the peripheral edge of the wheel working face |05 isapproximately tangent toa vertical plane through one .of the cutterteeth when the spindle 4 is at the .middleof its reciprocatory stroke.Rotation of the shaft .80, by means .of the motor .64 connected theretothrough the pulleys 68, 1.0 ,and belt 65, effects a rotation of thespindle 4 through the worm 58 and worm wheel 48. Shaft 08 vrotatesconcurrently with shaft ,60, .being geared thereto by gears |00 and |02which 1t-Will be .assumed have been vselected to provide the properdrive ratio, at `a speedequal to therotative speed of the spindle 4times the number of teeth 1 -onithemilling cutter 40 which is to beground. Any deviation vfrom this driveratio must be correctedbychanginggears |00 and v.|02 for other gears which will .provide .the same. Thecam '90 being Qdrivably carried by theshaft *.98 will therefore rotateand effect an `oscillatory movement of the lever L12 about its fulcrumpin 94, which movement, will be transmitted or converted into a verticalreciprocatory movementof the wedge 18, ball 15 and spindle '4 .as aunit. Reciprocation of the spindle concurrently with its rotation .ispermitted by the -extended length cf the .groove '56 whichallows it toslide relative to the key 50 affixed to the worm wheel 48.

Due to the contour of the working face |08 of the camiSB (see Figure)the spindle 4 in rising from its lowermost to its uppermost positionmoves first at a'uniformly increasing velocity for a limited distance,then at-a constant velocity for an extended distance,and formlydecreasing velocity of movement as it appreaches its uppermost position.ilts upward movement at constant velocity'V is substantiallysynchronized with its rotative movement by reason of the gearingtogether of the two shafts G0 and 98 (the slight distortive effectproduced by be summarized. A millfinally slows with unithe pivoting oflever f12gbeing-,neglectable in'view of theasmall-amplitudeof liftinvolved) ,with the result -thatthe upper vfaceaof each 'cutting toothFl movesin a continuousfplane, representedby the line |-01in Figure5,-during thatjperiod. The inclination of this plane-relative to thehorizontal depends kon .the effective length of the lever 12, whichisadjusted by shifting ,thev fulcrum pin supporting :bracket |08 :along-the rail either toward -or away from the cam 96. With the bracket |08located the properdistance from the cam, theplane ,referred to will be,parallel with thejplane of .the working face |05 of the grinding wheel8.

Since the spindle 4 must reciprocate 'the same number of .times perrevolution thereof as there are 4teeth 1 or likegporti'ons to be groundon the work piece, and since such number of reciprocations perrevolution directly affects the speed lof its axial movementindependently of its rotary movement, lthe proper location of Athebracket |08 on therail |f|6 to-obtain a desired angle of grind will needto be'varied' to accommodate work pieces having such different numbersof teeth. As-a convenience, lin facilitating theiproper locationof thebracket |08,v :markings or other reference points (notshown) vmaybeplaced on therail |'6 to ,indicate the positions lcorresponding to themost :commonly Y used combinations of desired clearance -angles'andcutter teeth numbers.

Prior tothe ,positioningaof the grinding wheel 8 by. adjustment oftheclamp |4,as earlier-referred to, the lead screw |20 is .backed out byrotating the handcrank |42 to withdraw the wedge 18 va sufiicientdistance to the left, as .viewed inFigure v2,so that the ball 16 .reststhereon near `thelower r`end of 4its inclined top face 192. l

The motors I3 and B4 are then started and the hand crank |42 is .rotatedtoraise the reciprocatory stroke of the spindle until the upper faces ofthe .cutter teeth just miss contacting the grinding wheel as they:successively rotate thereunder at the upper end of the spindle stroke.Hand wheel 5-2-is vthen interlocked with the lock nut |44 and thelatteris threaded up on the nut |26 to clamp them Linto frictional engagementwith the-star wheel |50 which is intermittently rotated by the arm |5|rotating with the spindle. Once each revolution thereafter the arm |5|engages the star Wheel 50 androtates the same one tooth, rotating .thenut |26 by the same degree and effecting an incremental advance of thelead screw |20 and wedge 18 toward the spindle, which in Yturn raisesthe reciprocatory stroke of the spindleand lfeeds the milling cutter 6or other workpiece a definite amount toward the grinding wheel 8.

Sinceithe cutter teeth 'i' successively engage the working .face |05 ofthe grinding wheel while moving in a plane parallel thereto, a surfacegrinding actionis obtained. Such a grinding action, as is Well known,has important advantages over -a plunge type .grind in accuracy andquality ofthe nished Work,.grinding wheel life, etc.; and

Y its achievement in a simply constructed machine providing automaticindexing and feeding ofthe work is one of the principal advantagesyobtained by -my invention.

It is also pointed out that by reason of the .instant machine employinga single `lobed cam to effect the reciprocation of the work piece, eachtooth or other portion of the latter being ground is advanced the same:distance into v.contact -with the grinding Wheel, Vresulting in thecomplete avoidance of ytooth Arun-out .from a .practical 7 standpoint.Further, the use of a single lobed cam arranged with a pivoted leverfollower adjustable in effective length, all in accordance with thisinvention, enables the machine to accommodate milling cutters or likework pieces of a variety of sizes and types.

The specific form and construction of the machine as shown in thedrawings and described herein was chosen with the view of building asingle machine or very small number thereof at a minimum cost, andit isappreciated that various structural modifications and refinements willreadily suggest themselves to persons skilled in this art.

I wish to further point out that the terms and expressions used hereinare to be considered in their descriptive rather than their limitingsense, and that the scope of my invention isV defined solely by theappended claims.

I claim: Y

l. In a machine for surface grinding milling cutters and the like, agrinding wheel, supporting means for said wheel, a spindle for carryinga milling cutter into contact with the wheel, means supporting saidspindle for rotary Yand reciprocatory movement, meansffor rotating thespindle at a uniform velocity, meansv for reciprocating the spindletoward and away from the wheel once for each tooth of the cutter duringeach revolution of the spindle, including a camhaving a 'working faceprovided with a uniform velocity lift section operative during theadvance stroire of the spindle, a lever actuated by the cam andoperatively engaging the spindle for transmitting the movement of thecam to the spindle, a fulcrum supporting said lever, and means foradjusting the fulcrum of the lever to vary the length of stroke and thusthe reciprocatory speed of the spindle.

2. In a surface grinding machine for multitoothed face milling cuttersand the like, a grinding wheel, supporting means for said wheel,aspindle for carrying a milling cutter, means supporting said spindlefor rotary and reciprocatory movement, means for rotating the spindle ata uniform velocity, means for reciprocating the spindle toward and awayfrom the wheel once for each tooth on the cutter during each revolutionof the spindle, including a cam having a working face provided with auniform velocity lift section operative in cooperation with the unilform speed of rotation of the spindle to cause the face of eachsuccessive cutter tooth to move in a continuous plane during itsengagement with the grinding wheel, and a lever operatively comiectingthe spindle to the cam for transmitting the movement of the cam to thespindle at a ratio such that Said plane extends parallel with theworking surface of the grinding wheel, said lever having a supportingfulcrum on said spindle supporting means.

3. In a milling cutter grinding machine, a rotatably and reciprocablymovable spindle having means adjacent one end for coaxially securing amilling cutter, means rotatably supporting said spindle and guiding itsreciprocatory movement, a grinding wheel having a generally iiatgrinding face opposite said spindle end and tilted from a positionnormal thereto by the amount of the clearance angle with which it isdesired to grind the faces of the cutter teeth, supporting means forsaid grinding wheel, means for rotating the spindle at a uniformvelocity and means for longitudinally reciprocating the spindle the samenumber of times per revolution thereof as the number of teeth on thecutter, said reciprocating means including a uniform velocity lift camoperative through a pivotally supported follower against the oppositeend of the spindle lever to effect a uniform lineal velocity ofthespindle during its advancement toward the grinding wheel, said leverhaving 'its pivotal support on said spindle supporting means theeffective length of said follower lever being adjustable to coordinatethe lineal and rotary velocities of the spindle in order that successiveteeth on the cutter engage the grinding wheel in the plane of its face.

4. In a milling cutter grinding machine, a spindle on which a grindingwheel may be mounted, a spindle on which a milling cutter may bemounted, supporting means for said spindles, means for rotating themilling cutter spindle at a uniform velocity, means for longitudinallyreciprocating the milling cutter spindle at a fred uency whose ratio tothe angular velocity of the milling cutter spindle is equal to thenumber of teeth on the milling cutter, including a cam having a workingface provided with a uniform velocity lift section operative during theengagement of each successive tooth of the cutter with the grindingwheel, a lever connected to the milling cutter spindle for transmittingthe movement of the cam to the milling cutter spindle, said lever Ybeing fulcrumed at one end and having its free end engaged by the cam,and means for adjusting the fulcrum of the lever to vary thereciprocatory stroke of the milling cutter spindle and thereby regulatethe speed at which the teeth of the milling cutter are fed to thegrinding Wheel, the fulorum for said lever being supported by saidspindle supporting means.

5. In a grinding machine for sharpening the teeth of milling cutters, amachine frame, a vertical spindle rotatably and reciprooably supportedtherein and provided with means at its upper end for coaXially securinga milling cutter to be sharpened, a Worm wheel thrustably supported bythe frame and having a coaXially slidable and rotary driving engagementwith the spindle below the milling cutter, driving means including afirst shaft journaled in the frame and carrying a worm in mesh with thelworm wheel, a rotary cam for effecting reciprocation of the spindle, asecond shaft in coaxial driving engagement with the cam and geared tothe rst shaft, a cam follower disposed transversely of the spindle andpivoted to the frame about a horizontal axis offset from the axis of thespindle, a variable height spacer member resting on the follower andvertically supporting the spindle thereon, and screw means geared to therotation ofthe spindle for slidably moving the spacer member apredetermined distance relative to the follower at the end of eachrevolution of the spindle.

6. An automatically self-indexing milling cutter grinding machine,comprising a Work spindle, a support journalling and reoiprocablyguiding said spindle, means for imparting a continuous axial rotation tothe spindle, a single lobe cam on said support geared to said means andadapted to impart a concurrent longitudinal reciprocation to thespindle, means for longitudinally shifting the reciprocatory stroke ofthe spindle, and an abrasive member mounted on said support relative tothe longitudinal and rotational movements of the spindle for contactingsuccessive teeth of the cutter with each reciprocation of the spindle.

'7. An automatic milling cutter grinding machine, comprising a rotatableand reciprocable spindle having means adjacent one of its ends forattaching a milling cutter, a support journalling and reciprocablyguiding said spindle, an abrasive member on said support, driving meansfor continuously rotating the spindle, and means including a singlelobed cam geared to said driving means and a pivoted follower inoperative engagement with the cam for effecting a reciprocation of thespindle in timed relation with its rotation, said cam and follower beingmounted on said support.

8. An automatic milling cutter grinding machine, comprising a rotatableand reciprocable spindle for carrying a milling cutter to be ground, asupport journalling and reciprocably guiding said spindle, an abrasivemember on said support, driving means for the spindle, gearing operablefrom said driving means to effect a continuous rotation of the spindle,other gearing including a constant velocity lift cam mounted on saidsupport and operable from said driving means to effect a continuousreciprocation of the spindle.

9. In a machine for surface grinding millingl cutters and the like, agrinding wheel, a spindle for carrying a milling cutter into contactwith the wheel, means for rotating the spindle at a uniform velocity,means for reciprocating the spindle toward and away from the wheel oncefor each tooth of the cutter during each revolution of the spindleincluding a cam having a work face provided with a uniform velocity liftsection operative during the advance stroke of the spindle and a leveractuated by the cam and operatively engaging the spindle fortransmitting the movement of the cam to the spindle, and a variableheight spacer member slidably resting on the lever and verticallysupporting the spindle thereon, and means for shifting said spacermember transversely of the spindle to shift the reciprocatory stroke ofthe spindle longitudinally of the spindle axis.

10. In a grinding machine for grinding milling Y cutters and the like, arotatable and reciprocable spindle for mounting the milling cutter to beground, a first gear in coaxial driving engagement with the spindle, asecond gear in mesh with the rst gear, a first shaft in coaxial drivingengagement with the second gear, a rotary cam, a second shaft in coaxialdriving engagement with the cam, a gear train drivingly interconnectingwith the first and second shafts, a lever having a free end slidablyresting on the cam and a fixed fulcrum laterally distant from both thecam and the spindle, a wedge member slidably spacing an end of thespindle from the lever, a screw-thread means interconnecting the wedgemember and said first gear for effecting endwise movement of the lwedgemember transversely of the spindle, and means supporting each of theaforesaid elements for their relative movements as defined.

1l. In an automatic milling cutter grinding machine, a rotatable andreciprocable spindle having means adjacent one of its ends for attachinga milling cutter, driving means for continuously rotating the spindle,and means including a single-lobed cam geared to said driving means anda pivoted follower operatively disposed between the cam and the oppositeend of the spindle for transmitting movement of the cam to the spindle,a variable thickness spacer means slidably interposed between the leverand said spindle opposite end, and means rotatively geared to thespindle for shifting said spacer means transversely of the spindle atthe end of each complete revolution of the spindle, and means supportingeach of the aforesaid elements for their relative movements as dened.

DON A. CARGILL.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,285,124 Gleason Nov. 19, 19181,326,462 Murch Dec. 30, 1919 1,841,244 Gstyr Jan. 12, 1932 2,108,310Grifng Feb. 15, 1938 2,332,420 Wildhaber Oct. 19, 1943 2,452,989 BrownNov. 2, 1948

